Thought girls were fickle? Blame the pill!

The pill, according to research, is ruffling up Mother Nature’s feathers by disrupting the natural selection patterns of women during their mate choice.

Women who undergo their natural ovulating cycles are said to be more innately attracted towards the archetypal alpha males. It is the female’s ability to smell out the immune system genes from male body odour that is used to discriminate between males for mate choice. Women supposedly seek out MHC (major histocompatibility complex) genes, which are genetically dissimilar to themselves. This enables a better promise of genetically healthy offspring, who can inherit a diverse set of immune system genes. MHC genes help with the synthesis of proteins within the immune system and assist in shaping the effects of pheromones. Pheromones are chemical messengers produced through perspiration at the surface of the skin and provide information about an individual’s potential genetic viability.

During a study on female selection, Dr Craig Roberts and his team analysed the MHC gene patterns of 100 women. They then asked these women to smell six male odour samples and choose which one they preferred. The experiment was carried out twice; the women were given nothing in the first experiment, but in the second experiment they were given the pill beforehand. There was a noticeable difference between the two experiments, with the participants who had taken the pill preferring the odours of genetically similar males. The researchers presumed that the effects of taking the pill can induce a pregnancy-like condition within the female body and so the need for choosing the genetically right partner becomes reduced. They believe that this was due to the suppression of certain hormones (oestrogen and progesterone).

“Not only could MHC-similarity in couples lead to fertility problems but it could ultimately lead to the breakdown of relationships when women stop using the contraceptive pill, as odour perception plays a significant role in maintaining attraction to partners”, Dr Craig Roberts concluded from his study.

Looking at these types of research, Dr Alvergne and Dr. Lumma have proposed that women who are on the pill could appear less sexually attractive to men than ovulating women. Again this might be because women who take the pill produce pregnancy state signals that steer away males. Nevertheless, there still remains a lot of doubt within this research area, particularly at how crucial MHC dissimilarity odour detection is when it comes to sexual selection.